WordPress getting on my nerves

While playing with the <pre> tag to get the Lisp code in one of my multithreaded queueing posts to look nice, using the formatting from lisppaste. I successfully downloaded Brian Mastenbrook’s lisppaste 2.3 code, broke the colorizing portion out from the web-serving and IRC-bot features, added the color scheme to my theme’s style.css, and tried to paste a formatted Lisp snippet’s HTML into the post box.

Unfortunately, something in WordPress decided to rearrange the closing tags to screw up the parenthesis matching and replace my &nbsp; with plain spaces, etc.